We propose organizing an International Conference entitled "Aging and Cellular Defense Mechanisms." The aim of the Conference is to bring together a number of scientists who study different age-related and potentially age-related cell processes for cross-fertilization of knowledge and to determine whether and to what extent the different cellular defense mechanisms can be integrated in a general hypothesis of aging. The general hypothesis of the Conference is the following: Cells are continuously exposed to a variety of internal and external stressors, potentially dangerous for the maintenance of the functional integrity of the cell (glucose, heat, oxygen free radicals, UV and gamma radiations, bacteria, viruses). In the course of evolution a number of mechanisms [DNA repair, production of heat shock and other stress proteins, enzymatic and non-enzymatic antioxidant defense systems, poly(ADP-ribose) polymerase activation] have emerged which allow the cell to cope with such a variety of potentially harmful agents. The hypothesis that these defense mechanisms constitute a network of cellular defense systems of critical importance to understand the aging process will bc carefully and critically examined by outstanding scientists. One of the aims of the Conference is to test the hypothesis that programmed cell death (apoptosis) plays an important role in the aging process (organ involution, cell loss), being. deeply related to cell proliferation and cell survival (deprivation of growth factors) and terminal differentiation. As most of these considerations are particularly relevant to the immune and the neuroendocrine system, two sessions will be devoted to these topics. A final session will ascertain whether antiaging strategies (e.g. dietary restriction) are so effective because they improve the functions of the most important cellular defense systems (DNA repair, antioxidants, etc.).